Spectacle lenses are known in many variations from the related art. There are spectacle lenses without nominal dioptric power and correction spectacle lenses, that is to say spectacle lenses having dioptric power. Dioptric power is the collective term for the focusing and the prismatic power of a spectacle lens.
In the case of correction spectacle lenses, a distinction is drawn between single-vision spectacle lenses and multifocal spectacle lenses. A single-vision spectacle lens is a spectacle lens in which only one dioptric power is present in respect of the design. A multifocal spectacle lens is a spectacle lens in which two or more visibly different parts having different focusing powers are present in respect of the design. Importance is attached in particular to bifocal spectacle lenses, namely multifocal spectacle lenses comprising two parts, usually for distance vision and near vision, and to progressive spectacle lenses, namely spectacle lenses comprising at least one progressive surface and an increasing (positive) power when the wearer of the spectacles looks down. Degressive spectacle lenses are uncommon, i.e., spectacle lenses comprising at least one progressive surface and a decreasing power (i.e., an attenuation of the power) when the wearer of the spectacles looks up.
GB 2498171 A, U.S. Pat. No. 8,496,329 B2, and WO 2014/124707 A1 basically describe single-vision spectacles having spectacle lenses including two lens segments, which are displaceable relative to one another, to be able to freely set the refractive power. Various mechanisms are described for displacing the lens segments relative to one another.
There are multifocal spectacle lenses of integral embodiment and also of compound, multipartite embodiment. Different variants of multifocal spectacle lenses in which, inter alia, bifocal or progressive segments are applied on a basic lens are described e.g., in EP 0 341 998 A1.
US 2012/194781 A1 describes spectacles of the generic type which are controlled by an eye tracker.
Current spectacle lenses are optimized for a visual point of the wearer of the spectacles through the spectacle lens. If the wearer of the spectacles moves only the eyes instead of the entire head, the calculated visual point no longer corresponds to reality. Since the eyes of human beings wander typically by up to 15° during normal vision behavior before the head is tracked, first-time wearers of progressive spectacles, for instance, have to relearn seeing with the new spectacles.